1996 Rodeo trans fluid drain fill / replace

I have a 96 rodeo, last trans service was at 89k miles now at 145k miles.

I am noticing some hesitancy to upshift from fist when truck is cold, and some occasional hunting/slipping at times. Local shops wont , or don't think it's a good idea to do a drain and fill or filter change.

Should I do a drain and fill, or do I run the risk or making matters worse (whats the difference if there is an internal issue developing anyway).

Or should I change the fluid and hope it clears things up.

Thanks